What Does
Acute Toxicity Estimate Mean?
Acute toxicity estimate (ATE) is a method for estimating the acute toxicity of a chemical or drug. In other words, a substance's potential to cause adverse effects a short time after exposure.
Safeopedia Explains Acute Toxicity Estimate
The acute toxicity of a chemical is measured by the number of deaths in test animals following exposure. Studies on acute toxicity help determine the dose that will cause death or serious illness when administered once or over a few instances within a 24-hour period.
These animal-based studies help researchers estimate the potential for acute toxicity in humans, as well as other critical pieces of information such as the potential target organs for the toxic effects.
The LC50 and LD50 Tests
Lethal concentration 50 (LC50) and lethal dose 50 (LD50) are two values that are often used as general indicators of a substance’s acute toxicity.
Both values are determined by exposing a sample group of animals to a chemical and then keeping them under clinical observation. In both cases, the aim of the test is to identify the concentration at which the chemical will be lethal to 50% of the sample group.
The main difference between the two is the pathway of exposure. LC50 measures the toxicity of an airborne chemical, while LD50 measures the toxicity of a chemical that has been administered orally, dermally, or intravenously.
Determining the Acute Toxicity of a Mixture
In the case of mixtures, acute toxicity is based on the ingredients in the mixture that have a known acute toxicity values.
The first step to calculating the ATE of a mixture is to identify the ATEs of each ingredient. These ATEs are taken from one of two sources:
GHS acute toxicity categories
Ingredients that are known to be benign (like water or harmless additives) are left out of the calculation.
The exact calculation used depends on the concentration of each ingredient. If the ingredients with unknown toxicity make up less than 10% of the total mixture, the ATE is calculated as follows:
If, however, the ingredients of unknown toxicity make up more than 10% of the mixture, the formula will be:
In cases where each ingredient in the mixture has the same toxicity classification under the GHS, the process of determining the ATE of the mixture is drastically simplified. Rather that performing a calculation, the mixture's ATE will be the same as all of its component ingredients. For example, if every ingredient is Category 3, then the mixture can also be considered Category 3.